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Water in attic ductwork

Eagleson's picture

Hello All,

While remodeling a bathroom this past spring, I nicked a flex duct in the ceiling and water started pouring out.  Quite a bit of moisture in most of the flex duct.  It's probably been this way for a long time

The 1978 ranch house is located in northern Indiana.

Heated with hot water baseboard, Cooled with a heat pump, all ductwork is in the unconditioned attic.  Attic is insulated with blown-in cellulose.  Most of the insulated flex duct lays on the insulation.  I close all the vents in the fall and add 2" rigid in the returns.

All of the flex will need to be replaced, but I want to solve the issue first.  A few options I've considered are covering the ducts with insulation, or conditioning the 3000sf attic, or sealing all the vents every fall (not convenient), or running a fan through the sytem in the off-season.  The ceiling height inside is too low to move inside the existing conditioned space.  Has anyone else encountered this before?  Thoughts on solving this issue?

Thanks!

You've got one or more air (post #216181, reply #1 of 4)

You've got one or more air leaks in your ductwork. If you're going to replace them all make sure the seams are sealed with duct sealer after they are taped.

Florida Licensed Building Contractor, 50 years experience in commercial remodeling, new homes, home remodeling and repairs and all types building maintenance.

So this is ductwork that is (post #216181, reply #2 of 4)

So this is ductwork that is used only for air conditioning?

Presumably what's happening is that air is migrating into the duct in the winter and moisture in the air condenses.  The two ways to deal with this are to totally seal the ducts in the winter (more than simply closing the registers) or somehow maintain a modest airflow (at the expense of lost heat).


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville

Air conditioning only, (post #216181, reply #3 of 4)

Air conditioning only, although as a heat pump, it does supplement heat early/late in the heating season.

Thanks, that was my thoughts too...I was hoping for an efficient one time repair for this problem.  I'll have to come up with an efficient way to seal the vents.  Somewhere around 16 supply and 3 returns. 

Running a fan for the life of the home seems like a huge waste of energy.

Another option that occurred (post #216181, reply #4 of 4)

Another option that occurred to me is to somehow maintain an airflow of "outside" air through the ducts when they are (mostly) closed off.


Of all the preposterous assumptions of humanity over humanity, nothing exceeds most of the criticisms made on the habits of the poor by the well-housed, well-warmed, and well-fed.  --Herman Melville